Category Archives: Cassandra

Internet Latency and Multi-Master Database Transactions

There’s 2 common misconceptions in engineering West Coast – East Coast data centers: that packets travel at the speed of light that database transactions must be 2-phase commit, and two masters cannot be located very far apart because of #1. … Continue reading

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Distributed Systems Laws Applied to Distributed Databases

Avery’s Law of Distributed Systems Reliability: “Distributed systems are more reliable when you can get a service from one node OR another. They get less reliable when a service depends on one node AND another. And the numbers combine multiplicatively, … Continue reading

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GitLab Validating Ceph in Production For Me

GitLab.com: Spikes are Outages. OSD = Ceph Object Storage Daemon It would be easy for me to criticize GitLab for using a distributed file system in production, especially Ceph, in AWS. I just wouldn’t roll that way. And it would … Continue reading

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Solving Java GC Pause Outages in Production

Just thinking about how to configure HAProxy with two backend Java servers to be HA, despite GC pauses. Java programs pause periodically to recycle temporary variables, known as garbage collection (GC). This is called a “GC Pause.” The description “Stop … Continue reading

Posted in Cassandra, GC Pauses, Java, Microservices, Open Source, Oracle, REST API Programming, Tech | Tagged | Leave a comment

HOWTO: CentOS 7/Redhat 7 Firewalld Setup for Cassandra Server

How to do initial firewalld configuration for Cassandra Server and Opscenter on CentOS/Redhat 7 with 2 network interfaces, in my case Dell 1950/2950. First: verify that your network interfaces are associated with a NetworkManager zone: # grep -i zone /etc/sysconfig/network-scripts/ifcfg-* … Continue reading

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